Matrix effects in collision cell
I see some strange effects with direct injection on column of brackish water.Briefly: When I directly inject brackish water on column, the response of the MRM is significantly lower than the same injection of tap water. What I see is that the product ion enhances (no adducts are formed) but the response of fragments in the collision cell decreases. See the example belowSome things i allready tested:- The collision energy has no influence on the effect. At higher energies, both product ion and fragments decreases.- The compounds involved are pesticides and especially phosphorous pesticides and phenyl urea herbicides. Triazines are not influenced!- When I use Offline SPE and inject 90% organic extract, the effects are gone.example:System: I_CLass FTN UPLC coupled to Xevo-TQS. 250µl extention loop.Column: Xselect HSS-T3 75x2.1mm, 2.5µmMobile Phase A: 95% H2O, 5% MeOH, 0.05% FAMobile Phase B: 100%acetonitril, 0.05% FAwater sample from North Sea estuary.My question is why it happens and off course how to loose the effects.